php图片的裁剪与缩放生成符合需求的缩略图

$src_img = "wallpaper.jpg";
$dst_w = 300;
$dst_h = 200;

<?php
list($src_w,$src_h)=getimagesize($src_img); // 获取原图尺寸
$dst_scale = $dst_h/$dst_w; //目标图像长宽比
$src_scale = $src_h/$src_w; // 原图长宽比
if($src_scale>=$dst_scale)
{
// 过高
$w = intval($src_w);
$h = intval($dst_scale$w);
$x = 0;
$y = ($src_h - $h)/3;
}
else
{
// 过宽
$h = intval($src_h);
$w = intval($h/$dst_scale);
$x = ($src_w - $w)/2;
$y = 0;
}
// 剪裁
$source=imagecreatefromjpeg($src_img);
$croped=imagecreatetruecolor($w, $h);
imagecopy($croped,$source,0,0,$x,$y,$src_w,$src_h);
// 缩放
$scale = $dst_w/$w;
$target = imagecreatetruecolor($dst_w, $dst_h);
$final_w = intval($w$scale);
$final_h = intval($h$scale);
imagecopyresampled($target,$croped,0,0,0,0,$final_w,$final_h,$w,$h);
// 保存
$timestamp = time();
imagejpeg($target, "$timestamp.jpg");
imagedestroy($target);
?>